Method of use of catheter with working head having selectable impacting surfaces

ABSTRACT

A catheter and method of use for engaging material within the body of a living being to accomplish a medical and/or surgical procedure, e.g., form and enlarging an opening in a restriction in a vessel, duct, or lumen formed by the material, or to destroy a stone or other hard body formed of the material. The catheter comprises an elongated body portion and a rotatable working head located at the distal end of the catheter. The catheter is positioned with the working head adjacent the material to be enlarged. The working head comprises at least two, non-sharp, impacting surfaces, each of differing aggressiveness of restriction opening action. The less aggressive of the impacting surfaces is brought into engagement with the material when the working head is rotated in one rotational direction. The more aggressive of the impacting surfaces is then rotated in the opposite rotational direction and brought into engagement with the material to complete the procedure.

This application is a Continuation-In-Part of our earlier applicationSer. No. 395,109, now U.S. Pat. No. 5,042,984, filed on Aug. 17, 1989,entitled Catheter With Working Head Having Selectable ImpactingSurfaces, which is assigned to the same assignee as this invention andwhose disclosure is incorporated by reference herein.

This invention relates generally to medical instruments and theirmethods of use, and more particularly to catheters and methods of usefor enlarging openings in vessels, ducts, or lumens, in living beings.

BACKGROUND OF THE INVENTION

Various types of catheter instruments have been suggested or disclosedin the patent literature for effecting non-invasive or minimallyinvasive surgical or medical procedures within the body of a person oranimal. For example, in U.S. Pat. No. 4,445,509 (Auth) there isdisclosed a recanalization catheter designed specifically for cuttingaway hard, abnormal deposits, such as atherosclerotic plaque from theinside of an artery while supposedly preserving the soft arterialtissue. That recanalizing catheter includes a sharp-edged, multi-fluted,rotating cutting tip mounted at the distal end of the catheter andarranged to be rotated by a flexible drive shaft extending down thecenter of the catheter. The rotation of the cutting head is stated asproducing a "differential cutting" effect, whereupon relatively harddeposits are cut away from relatively soft tissue. Suction ports areprovided in the cutting tip to pull the hard particles produced by thecutting action into the catheter for removal at the proximal end thereofso that such particles thereof so that such particles do not flowdistally of the catheter where they could have an adverse effect on thepatients' body.

It has been determined that the use of sharp rotary cutting blades in arevascularization catheter can have various adverse effects on arterialtissue, e.g., snagging, cutting, or otherwise damaging the tissue of theartery wall.

In our U.S. Pat. No. 4,700,705 (Kensey et al.), assigned to the sameassignee as this invention, and whose disclosure is incorporated byreference herein, there is disclosed and claimed catheters and methodsof use for effecting the opening of a vessel, duct or lumen, such as theopening of a atherosclerotic restriction in an artery or the opening ofa fallopian tube. The catheters of that invention consist of elongatedflexible members of sufficient flexibility to enable them to be readilypassed through the body of the patient to the situs of the procedure tobe accomplished, e.g., the location of the atherosclerotic plaque in theartery to be opened. A working head is mounted at the distal end of thecatheter and is arranged for high-speed rotation about the longitudinalaxis of the catheter. In some embodiments the catheter may eject fluidat the working head to expedite the procedure.

In another of our U.S. patents, namely, U.S. Pat. No. 4,747,821 (Kenseyet al.) (hereinafter referred to as the '821 patent), also assigned tothe same assignee as this invention and whose disclosure is incorporatedby reference herein, there is disclosed and claimed other cathetersparticularly suited for revascularization of arteries. Each of thosecatheters includes a rotary working head having at least one non-sharpimpacting surface to effect material removal without cutting. Moreover,those catheters are arranged to eject fluid adjacent the working head toexpedite the procedure. When such a catheter is used for treatingatherosclerotic disease by recanalizing arteries, the catheter is guidedthrough the vascular system of the patient to the site of the vascularocclusion or blockage (restriction) that has been determined to exist sothat the rotary working head is located immediately adjacent therestriction. The working head is then rotated about the longitudinalaxis of the catheter at a high rate of speed, e.g., from 10,000 rpm to200,000 rpm. At the same time, fluid is passed through the catheter andout of its distal end adjacent the working head.

The opening of the restriction to allow freer flow of blood is effectedby the dilation and/or selective emulsification properties of thecatheter's working head. In this connection, during the rotation of theworking head fluid jets exiting the distal end of the catheter at theworking head or immediately accelerated laterally by portions of theworking heads so that they are broken up into small segments thatdevelop considerable momentum as they are flung out in all directions,including radial directions, toward the wall of the artery. These liquidsegments transfer their momentum to the artery wall, forcing the arterywall outward laterally in all directions thereby aiding in dilating it.Moreover, the radial pressure developed by the rotating working head issubstantial and can raise local static pressure immediately adjacent theworking head by approximately 100 to 200 millimeter of Hg. Thisincreased pressure on the artery wall contiguous with the rotatingworking head is not due solely to the impact of the liquid segmentsthereon, but also due to the recirculation of the liquid surrounding theworking head. In this connection, the rotation of the working headproduces a powerful, toroidal shaped vortex contiguous with the workinghead.

The vortex, in addition to augmenting the application of increasedpressure to the artery wall contiguous with the working head, also hasthe effect of recirculating any particles that may have been broken offfrom the material forming the arterial restriction by the impact of therotary working head with that material. In particular the working head,with its non-sharp impacting surfaces differentiates atherosclerotictissue from normal tissue through the inherent differences in thetissues' physical properties and organizational patterns. Therefore,when the catheter is passed transluminally through the diseased artery,its working head serves to emulsify occlusive lesions not covered withfibrous plaque by repeatedly impacting the material forming therestriction as the working head is rotated, and with minimal risks ofpuncture or perforation of the contiguous artery wall. Theemulsification process is accomplished by the repeated impaction of thenon-sharp impacting surfaces on the material forming the restriction.This action causes the material to be broken away in small particles.The vortex flow at the working head insures that any particles producedby the impacting action are drawn back into contact with the impactingsurfaces of the rotating working head. Accordingly, those particles arerepeatedly impacted over and over, with each impaction reducing the sizeof the particles further until the resulting particle size issufficiently small, e.g., 95% have a surface area less than that of ared-blood cell, that they can be permitted to flow to downstream tissuewithout causing any significant deleterious effects to the patient.

Other catheters for enlarging an opening in a vessel, duct or lumen havebeen disclosed and claimed in the following United States patents,assigned to the same assignee of this invention, and whose disclosuresare also incorporated by reference herein: U.S. Pat. No. 4,589,412(Kensey); U.S. Pat. No. 4,631,052 (Kensey), U.S. Pat. No. 4,686,982(Kensey et al.), U.S. Pat. No. 4,749,376 (Kensey et al.) and U.S. Pat.No. 4,790,813 (Kensey).

For some procedures involving the enlarging of openings in vessels,ducts and lumens, it may prove beneficial or more effective to utilizecatheters whose working heads include impacting surfaces of differingaggressiveness which may be selectively brought into engagement with therestriction to be opened. Moreover, such catheters can be utilized toeffect other procedures within the body of a living being, e.g., thedestruction of stones or other hard bodies. Examples, of other priorcatheters and/or instruments for destroying stones within the body of aliving being are the following which are assigned to the same assigneeas this invention: U.S. Pat. No. 4,679,558 (Kensey et al.) and U.S. Pat.No. 4,811,735 (Kensey et al.).

In our aforementioned application there is disclosed and claimed methodsof revascularizing partially or fully occluded arteries utilizing arotating working head having at least two impacting surfaces, one ofmore aggressiveness than the other. The subject invention relates tosuch methods.

OBJECTS OF THE INVENTION

Accordingly, it is the general object of this invention to provide amethod of use of an instrument for revascularizing partially or totallyoccluded arteries in living beings.

It is a further object of this invention to provide a method of use ofan instrument which includes a rotary working head having at least twonon-sharp impacting surfaces each of which exhibits a differentaggressiveness in action when brought into engagement with material inthe artery forming the occlusion.

It is yet a further object of this invention to provide a method of useof an instrument which includes a rotary working head having at leasttwo non-sharp impacting surfaces, one of which exhibits lessaggressiveness in action when brought into engagement with a relativelysoft material, e.g., a thrombus, forming the occlusion, and the other ofwhich exhibits more aggressiveness in action when brought intoengagement with a relatively hard material, e.g., calcific tissue,forming the occlusion.

SUMMARY OF THE INVENTION

These and other objects of the instant invention are achieved byproviding a method of recanalizing an artery located in the body of aliving being utilizing an instrument comprising an elongated bodyportion and a moveable working head. The artery is partially or fullyoccluded by material located therein, with the material comprising atleast one, relatively soft or relatively hard, component. The workinghead is arranged for rotation about a longitudinal axis of theinstrument and comprises a first non-sharp, impacting surface exhibitinga first predetermined aggressiveness of action when engaging materialcomprising the relatively soft component, and a second non-sharp,impacting surface exhibiting a second and greater predeterminedaggressiveness of action when engaging material comprising therelatively hard component.

The method comprises introducing the instrument into the body so thatthe working head is adjacent the material. The working head is rotatedabout the axis. The first impacting surface is brought into engagementwith the material as the head is rotated if the material comprises therelatively soft component. Alternatively, the second impacting surfaceis brought into engagement with the material as said head is rotatedabout the axis if the material comprises the relatively hard component.

In accordance with one preferred method the catheter is used with itsworking head rotating in one direction to produce the less aggressiverevascularization action and is rotated in the opposite direction toproduce the more aggressive revascularization action.

DESCRIPTION OF THE DRAWINGS

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a recanalizing catheter having a workinghead constructed in accordance with this invention opening a restrictionin an artery;

FIG. 2 is an enlarged front elevational view of the working head shownin FIG. 1;

FIG. 3 is an enlarged side elevational view of the working head shown inFIG. 1;

FIG. 4 is an enlarged top elevational view of the working head shown inFIG. 1; and

FIG. 5 is a greatly enlarged, transverse (i.e., perpendicular to theaxis of rotation of the working head) sectional view of a portion of theworking head shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in detail to the various figures of the drawing whereinlike reference characters refer to like parts, there is shown at 10 inFIG. 1 a catheter apparatus constructed in accordance with the subjectinvention. The catheter 10 is particularly suited for recanalizingatherosclerotic deposit-occluded or restricted arteries, but can be usedfor enlarging the opening through any type of vessel, duct, or lumenwithin the body of a living being.

The portion of catheter 10 shown in FIG. 1 constitutes its distal endand is shown in the process of opening a restriction 12 in an artery 14.Such arterial restrictions are formed by the deposit of atheroscleroticplaque or some other materials(s), such as wax and/or calcifiedatheroma, thickened and/or ulcerated intima, etc.

The catheter 10 basically comprises an elongated flexible tubular bodymember or jacket 16 at the free or distal end 18 of which is located arotatable working head 24. The working head 24 is generally similar tothat described in the '821 patent except for the inclusion of impactingsurfaces of differing degrees of aggressiveness of action. Thus, theworking head 24 of this invention basically comprises two impactingsurfaces 24A and two impacting surfaces 24B which are arranged to beselectively brought into engagement with the material forming therestriction 12 as the catheter's working head is rotated about thecatheter's longitudinal axis in either of two rotational directions. Theimpacting surfaces 24A have a different radius of curvature (andoptionally--some rake or clearance) than the impacting surfaces 24B toexhibit respective and different degrees of aggressiveness ofrestriction opening action, with surfaces 24A being less aggressive inaction than surfaces 24B.

The details of the working head 24 and its impacting surfaces 24A and24B will be described later. Suffice it for now to state that theworking head is arranged to be rotated at a high rate of speed, e.g.,10,000 to 200,000 RPM or higher, about the longitudinal axis 25 (FIGS. 3and 4) of the catheter in one rotational direction (e.g.,counterclockwise as viewed in FIGS. 1 and 2) to bring the working head'simpacting surfaces 24A into engagement with the material forming therestriction 12. The catheter is then advanced in a longitudinally in adistal direction through the restriction. This action opens therestriction, i.e., forms a passageway P for blood to flow therethrough,in the same manner as described in detail in U.S. the '821 patent. Inparticular, the passageway P is opened by dilating the stenotic oroccluded area (which may or may not be covered by fibrous plaque) and/orselectively removing calcified thrombotic, or fatty tissue unprotectedby fibrous plaque while allowing the artery wall to remain intact. Theless aggressive action of the working head's impacting surfaces 24A onthe material forming the restriction ensures that the passageway P isproduced with minimal danger of damage to the tissue of the artery. Oncethe passageway P has been formed the working head 24 may then be rotatedin the opposite rotational direction (e.g., clockwise as viewed in FIGS.1 and 2), again at a high rate of speed, and withdrawn, i.e., passed inthe longitudinally proximal direction, through the passageway P so thatits impacting surfaces 24B engage the material contiguous with thepreviously formed/enlarged passageway to enlarge or dilate it further.

The catheter jacket 16 is formed of any suitable material, e.g.,plastic, and has a small outside diameter. In the preferred embodimentshown herein, the outside diameter is approximately 1.5 mm (5 French) orless. This size catheter is merely exemplary. Thus, in accordance withthis invention the catheter can be constructed as small as 2 French (0.6mm). The means for effecting the rotation of the working head is notshown but can comprise any suitably constructed system such as but notlimited to those disclosed in the foregoing U.S. Pat. Nos. 4,686,982,4,747,821, and U.S. application Ser. No. 938,698 filed on Dec. 5, 1986,and entitled "Catheter With Means To Prevent Wear Debris From Exiting,"now abandoned.

Irrespective of the construction of the drive system utilized it iscoupled to the working head 24 so that the working head is rotated atthe high rate of speed by a proximately located motor (not shown). Ascan be seen clearly in FIGS. 3 and 4 the working head 24 includes acentral shank portion or axle 26 projecting proximally therefrom. Theaxle 26 is supported in a central bore (not shown) of a bushing 28fixedly mounted at the distal end of the catheter's jacket 16. Like thecatheters disclosed in the '821 patent a liquid is preferably passeddown through the catheter jacket 16 through four equidistantly spacedgrooves (not shown) extending down the central bore of the bushing 28and exiting at ports 30 (only one of which can be seen in FIG. 1) to aidin the enlargement of the opening in the vessel, duct or lumen. Furtherstill, the liquid which is passed down the catheter can, if desired, beoxygenated to eliminate distal ischemia when the catheter is used forarterial restriction opening procedures. Also, if desired, nitrates,contrast media, or other drugs can be added to the liquid as neededduring the procedure.

The details of the working head 24 will now be discussed. The workinghead 24 basically comprises a convex shaped tip of a generallyhemispherical shape and having a pair of generally planar diametricallydisposed relieved side surfaces or faces. This structure forms theheretofore identified impacting surfaces 24A and 24B. In particularthose impacting surfaces are formed by rounded or radiused edges of arespective pair of cam surfaces 24C and 24D. The cam surfaces themselvesare formed by the outer convex (e.g., spherical) surface portions of theworking head located between a pair of relieved planar surfaces 24E and24F. The interface of the cam surface 24C and the relieved surface 24Eforms one impacting surface 24A, while the interface of the cam surface24D and the relieved surface 24F forms the other impacting surface 24A.As can be seen in FIG. 5 the impacting surfaces 24A are rounded(radiused) in a plane perpendicular to the axis of rotation of theworking head so that each is not sharp, e.g., is in the range ofapproximately 0.001 inch to approximately 0.008 inch, although in thescale of FIGS. 1-4 of the drawing they appear to be a sharp line. Theportion of each of the relieved surfaces 24E and 24F at their interfacewith the cam surfaces 24C and 24D, respectively, are further relieved,ground, or cut away to form relieved lip surfaces 24E' and 24F',respectively. The interface of the cam surface 24C and the relieved lipsurface 24F' forms one of the aggressive impacting surface 24B, whilethe interface of the cam surface 24D and the relieved lip surface 24E'forms the other aggressive impacting surface 24B. The aggressiveimpacting surfaces 24B are also rounded (radiused) in a planeperpendicular to the axis of rotation of the working head so that eachis not sharp, e.g., is of a radius of 0.0005 inch to approximately 0.002inch, although even in the scale of the enlarged sectional view of FIG.5, they appear to be a sharp line.

The relieved surfaces 24E and 24F taper toward each other in thedirection toward the distal end of the working head, with the maximumspace between the relieved surfaces being slightly larger than thediameter of the working head shaft or axle. The flatted or relievedsurfaces 24E and 24F are preferably within the range of 0 to 10 degreesnegative rake to the radius R forming the spherical cam surfaces 24C and24D, while the flatted or relieved surfaces 24E' and 24F' may be at amore aggressive angle, e.g., from three degrees negative to ten degreespositive rake, to radius R of the cam surfaces 24C and 24D. Moreover, ifdesired, the clearance of the working head cam surfaces contiguous withthe non-aggressive and/or aggressive impacting surfaces 24A and 24B,respectively, may be configured as desired, depending upon the desiredapplication of the instrument.

By virtue of the shape of the working head, the free or open end ports30 of two diametrically opposed grooves are uncovered or exposed by therelieved surfaces 24E and 24F to enable fluid passing through thosegrooves to exit the ports in the same manner as described in the '821patent. As will be appreciated by those skilled in the art, since theworking head rotates, the relieved surfaces of the working headsequentially cover and uncover diametrically opposed ports at the distalends of the grooves. This action breaks up the fluid streams exitingfrom those ports into segments or slugs which are distributed in agenerally hemispherical pattern about the working head. The liquid slugshave some radial component and develop tremendous momentum as they areflung outward toward the artery wall. The momentum of the slugs istransferred to the artery wall thereby forcing the artery wall laterallyoutward in all radial directions thereby dilating the vessel asdescribed in the aforementioned patent.

The rotation of the working head about the longitudinal axis 25 alsoproduces a powerful toroidal shaped vortex contiguous with the workinghead. The vortex has the effect of recirculating any particles that arebroken off from the restriction by the impact of the rotating workinghead with the material forming the restriction. Thus, if the materialforming the restriction is such that particles are broken away, they arecirculated by the vortex and carried back into the rotating working headwhere they are progressively reduced in size to the point where they cansafely flow distally.

It must be pointed out at this juncture a catheter constructed inaccordance with this invention can be utilized with its working headrotating in the rotational direction to bring the more aggressiveimpacting surfaces 24B into engagement with the material forming therestriction in the first instance (i.e., without prior use of the lessaggressive impacting surfaces 24A). Thus, in some cases it may not benecessary to first open the restriction somewhat by the use of the lessaggressively acting impacting surfaces 24A of the working head. Furtherstill, even if the restriction is first opened by the use of the lessaggressively acting impacting surfaces 24A the passage of the workinghead through the passageway P while rotating in the rotationaldirection, e.g., clockwise in FIGS. 1 and 2, to bring the moreaggressively acting impacting surfaces 24B into engagement with thematerial forming the restriction at the passageway P can be accomplishedfrom either the proximal to distal direction or vice versa.

It must also be pointed out that while the working head shown anddescribed herein includes two of each of the impacting surfaces, 24A and24B such a construction is not required. Thus, the working head may beconstructed to include only one impacting surface of each type, i.e.,one surface 24A and one surface 24B, or more than two of each suchsurface, depending upon the application desired.

Moreover, as mentioned earlier, the working head and/or an instrumentmaking use of the working head of this invention can be utilized todestroy a stone or other hard body located within the body of a livingbeing. That action is accomplished by placing the instrument so that theworking head is adjacent the stone, whereupon the working head isrotated in either rotational direction, as desired, to create the vortexflow and thereby pull the stone into engagement with the impactingsurfaces 24A or 24B (depending upon the direction of rotation). Thisaction breaks the stone into particles which are recirculated by thevortex flow back into engagement with the impacting surfaces so thatthey are further reduced in size (pulverized).

As should be appreciated by those skilled in the art, the selectiveengagement by either the less aggressive impacting surfaces or the moreaggressive impacting surfaces (such as is preferably accomplished by theselection of the desired direction of rotation of the head to bring that(those) impacting surface(s) into engagement with the tissue or materialforming the restriction, be it a partial or total occlusion), providesthe physician with a powerful modality for revascularizing an artery.Thus, rotation of the working head in one rotational direction about thelongitudinal axis of the device to bring the less aggressive impactingsurfaces into action can be used to revascularize an artery havingrelatively soft material deposits, e.g., fatty tissue, thrombus, etc.,therein, while rotation of the working head in the opposite rotationaldirection to bring the more aggressive impacting surfaces into actioncan be used to effect recanalization of relatively hard deposits ortissue, e.g., calcific tissue, fibrous cap tissue, etc., which requiremore energy to effect the pulverization thereof.

Without further elaboration, the foregoing will so fully illustrate ourinvention that others may, by applying current or future knowledge,readily adopt the same for use under various conditions of service.

We claim:
 1. A method of recanalizing an artery located in the body of aliving being utilizing an instrument comprising an elongated bodyportion and a moveable working head, said artery being partially orfully occluded by material located therein, said material comprising atleast one portion made up of a relatively soft component or a relativelyhard component, said working head being arranged for rotation about alongitudinal axis of said instrument in either of two oppositerotational directions and comprising a first non-sharp, impactingsurface exhibiting a first predetermined aggressiveness of action whenengaging material comprising said relatively soft component, and asecond non-sharp, impacting surface exhibiting a second and greaterpredetermined aggressiveness of action when engaging material comprisingsaid relatively hard component, said method comprising introducing saidinstrument into said body so that said working head is adjacent saidmaterial to bring one of said impacting surfaces into engagement withsaid material, selectively rotating said working head about said axis inone of said rotational directions, said rotational direction beingselected depending upon which of said impacting surfaces is to bebrought into engagement with said material, whereupon if said materialto be engaged by said working head comprises said relatively softmaterial said working head is rotated in the rotational direction tobring said first impacting surface into engagement with said materialand if said material to be engaged by said working head comprises saidrelatively hard material said working head is rotated in the oppositerotational direction to bring said second impacting surface intoengagement with said material.
 2. The method of claim 1 wherein saidrelatively soft component comprises fatty tissue.
 3. The method of claim1 wherein said relatively soft component comprises thrombus.
 4. Themethod of claim 1 wherein said relatively hard component comprisescalcific tissue.
 5. The method of calim 1 wherein said relatively hardmaterial comprises fibrous cap tissue.
 6. The method of claim 1 whereinsaid material comprises a portion of said relatively soft component anda portion of said relatively hard component, said method including thesteps of rotating said working head in said one direction for bringingsaid first impacting surface into engagement with said relatively softcomponent, and rotating said working head in said opposite direction forbringing said second impacting surface into engagement with saidrelatively hard component.
 7. The method of claim 6 wherein saidrelatively soft component comprises fatty tissue.
 8. The method of claim6 wherein said relatively soft component comprises thrombus.
 9. Themethod of claim 6 wherein said relatively hard component comprisescalcific tissue.
 10. The method of claim 6 wherein said relatively hardmaterial comprises fibrous cap tissue.
 11. A method of recanalizing anartery located in the body of a living being utilizing an instrumentcomprising an elongated body portion and a movable working head, saidartery being partially of fully occluded by material located therein,said material comprising at least one relatively soft component and atleast one relatively hard component, said working head being arrangedfor rotation about a longitudinal axis of said instrument and comprisinga first non-sharp, impacting surface exhibiting a first predeterminedaggressiveness of action when engaging material comprising said at leastone relatively soft component, and a second non-sharp, impacting surfaceexhibiting a second and greater predetermined aggressiveness of actionwhen engaging material comprising said at least one relatively hardcomponent, said method comprising the steps of introducing saidinstrument into said body so that said working head is adjacent saidmaterial including said at least one relatively soft component, rotatingsaid working head about said axis and bringing said first impactingsurface into engagement with said at least one relatively softcomponent, and positioning the working head adjacent the materialincluding said at least one relatively hard component, rotating saidworking head about said axis and bringing said second impacting surfaceinto engagement with said at least one relatively hard component. 12.The method of claim 11 wherein said relatively soft component comprisesfatty tissue.
 13. The method of claim 12 wherein said relatively hardcomponent comprises calcific tissue.
 14. The method of claim 12 whereinsaid relatively hard material comprises fibrous cap tissue.
 15. Themethod of claim 11 wherein said relatively soft component comprisesthrombus.
 16. The method of claim 15 wherein said relatively hardcomponent comprises calcific tissue.
 17. The method of claim 15 whereinsaid relatively hard material comprises fibrous cap tissue.